Process for flameproofing textile materials



Patented Feb. 9, 1954 UNITED STATES TENT OFFICE PROCESS FOR FLAMEPROOFING TEXTILE MATERIALS 1 N 0 Drawing. Application September 4, 1951, Serial No. 245,089

6 Claims.

'This'invention relates to flameproofing compositions and more particularly to titaniumantimony-containing compositions useful in rendering cellulosic materials flame-resistant. More-specifically, it relates to novel monobasic acid-organic solvent solutions containing titanium and antimony and to novel methods for their preparation and application to cellulosic, especially textile, materials to impart flame-retardant characteristics thereto.

The preponderant use of cellulose and its derivatives in the fabrication of various articles, particularly textiles, clothing and yarns, has long been recognized as fire hazardous. Thus, cellulosic fabrics of commerce such as rayon and cotton goods are readily ignited by a flame, and when employed in lightweight clothing or heavier-weight material having a pile finish, such as obtained by brushing regenerated cellulosic textiles, e. g., woven or knitted viscose goods, present an appreciable fire hazard to the wearer.

Numerous attempts have been made to render cellulosic materials less combustible as by applying treating agents thereto such as ammonium phosphate, ammonium sulfamate, tin and antimony-oxides, or chlorinated hydrocarbons. However, such treatments have not proved satisfactorily effective from both a fiameand laundryproofing standpoint. More recently, highly useful monobasic acid solutions of titanium and antimony of the type contemplated in the coi pending U. Sapplication of Frank W. Lane and myself, Ser. No. 724,242, (now Patent No. 2,570,566) filed January 24, 1947, as well as in my. application Sen No. 170,265 (now Patent l lo. 2,607,729) filed June 24, 1950, also copending, have proved highly and generally effective for these purposes. In accordance with said applications, the cellulosic material '(cotton, rayon, etc., or like fabric or yarn) is suitably treated or impregnated. with .a stable, aqueous monobasic acid '(HCI) solution of titanium and antimony containing from 25 toabout 500 .g./l. of the combined oxides of itaniumand antimony, the atom ratio of antimony to titanium in said solution not exceeding 2 and the Weight ratio of titanium to antimony therein ranging up to 10. Excess treating solution is thereafter removed from the impregnated product by conventional draining or squeezing. The treated material is then soaked in a neutralizing bath comprising a relatively mild-alkaline reagent, e. g., sodium carbonate, ammonium carbonate, or ammonium hydroxide, etc, and is then conventionally washed by v,passing it through a washing bath of water or a soapy fluid, during which reaction by-prod- 2 ucts and loosely held hydrated titanium. and antimony oxides are removed.

Washing the product by regular laundry procedures results in about 515% by weightof the combined oxides remaining in the cloth-about'a 50% oxides pickup from the originalimpregnation step. Disadvantageously the other half remains in solution in the interstices of the fabric and is precipitated during the neutralizing treatment and ultimately lost through washing out. When an attempt is made to increasethe emciency of the treating agent by diluting the impregnating solution with water, this is unsuccessful because at the lowered concentration the stable treatment acquired by the fiber falls below the level necessary for good flame-resistant properties. In consequence, the necessity of leaving an excess of treating solution in the textile fibers going to the neutralization has militated against the practical treatment of yarn in socalled package form, e. g., relatively thick layers of yarn bound on a core, because of the impossibility of efiectively washing out of such package precipitated hydroxides derived from the neutralization. Furthermore, when relatively dark-colored fabrics are treated with these solutions, disadvantageously light-colored patches or smears (termed grey ghosts) objectionably develop on such fabrics during the neutralization step and persist through laundering. This arises from the presence of residual oxide deposit in the cloth due to the neutralization treatment.

It is among the objects of this invention" to overcome the foregoing disadvantages in certain applications of the titanium and antimony flameretardant treating compositions of said copending applications Ser. No. 724,242 and 170,265 and to provide a generally improved form of such type of fiameproofing compositions. Further objects include the provision of novel methods 'for preparing said compositions and applying'them to cellulosic substances, especially textiles, whereby a flame-resistant and laundryproof type of product can be readily obtained, and the provision of a novel composition adapted to advantageously increase the efficiency of titanium and antimony solutions when applied to said textiles, as well as to improve thecharacter and appearance of textiles treated therewith. Another object is to provide a novel composition effectively useful in treating so-called package types'sof materials, and which, when applied to 'darkecolored fabrics, will not result in the appearanceoi light-colored patches or -grey ghosts" on the" cloth after laundering. A further object is to desirably broaden the fields of applications of titanium and antimony treating solutions so that fiameproofing characteristics can be imparted to materials not previously amenable to such treatment. Other objects and advantages of the invention will be evident from the ensuing description thereof.

These and other objects are attained in this invention which involves the provision of a treating composition adapted to impart flame-resistant characteristics to cellulosic substances, especially textiles, said composition comprising an aqueous acidic solution of titanium and tervalent antimony diluted with a dissolved, volatile, water-soluble, and initially stable organic liquid, the weight ratio of titanium to antimony in said solution being not in excess of 10, the atom ratio of antimony to titanium not exceeding 2, and the amount of dissolved organic liquid being not greater than 70% by weight.

.In adapting my invention, I further dilute a stable, flame-retardant monobasic acid antimony-titanium solution, prepared in accordance with the disclosures of said copending applications Ser. Nos. 724,242 and 170,265, with an initially stable, soluble organic liquid which is at least as volatile as water under the conditions of its evaporation, either boils below 100 C., or forms aqueous azeotropes boiling below 100 0., and is readily soluble or at least soluble, in H2O. As contemplated in said application Ser. No. 724,242, the titanium-antimony solution can be prepared by combining commercial TiCl4 with antimony oxide in the presence of water, with such proportion of reagents being employed in the mixing that a final solution results containing from about 12-600 g./l. of the combined oxides, TiO2 and Sb20a, where the weight ratio Ti/Sb does not exceed 10, and the atomic ratio Sb/Ti does not exceed 2. More specifically, the solution can contain from about 140 to 200 g./l. of titanium and from 250 to 475 g./l. of antimony (calculated as TiOz and Sb2O3) and from 200-5'75 g./l. of chlorine (calculated as I-ICl) a preferred form of solution having an antimony and titanium concentration ranging from about 260-325 g./1. Sb203, about 140-170 g./l. TiO2, and about 350-450 g./l. I-ICl. Alternatively, and as contemplated in said application Ser. No. 170,265, solutions of similar concentration can be prepared by dissolving in water or water containing an acid such as hydrochloric, acetic, chloracetic, etc., suificient solid, drv, aqueous-medium-soluble concentrate comprising the soluble chlorides of titanium and antimonv in which the atom ratio of antimony to titanium is not more than 2 and not less than one-twenty-fifth, said concentrate being the reaction product of antimony oxide with titanium tetrachloride with enough water present to convert any unreacted TiCl4 to titanium oxychloride in accordance with the equation:

In accordance with this invention, titaniumantimony solutions of the above types are modified through the addition or admixture therewith of from about 5-240 parts by weight, but not to exceed the solubility limit, of a water-soluble, volatile organic liquid, such as a monohydroxy alcohol, ester, ketone, or nitrile containing up to 4 carbon atoms each, or mixtures thereof, per 100 parts of the original solution. Preferably, from about 20% to 100% of its weight of a dissolved volatile monobasic alcohol such as methanol,

4 ethanol, isopropanol, tertiary butanol, secondary butanol, etc., is incorporated therein.

The organic solvent-diluted or modified composition thus obtained is then employed to treat a cellulosic material having hydroxy groups free to combine with titanium to impart desired flame-resistant properties thereto. Examples of such material include wood, cellulosic films, cloth, woven fabrics, paper, cellophane, etc., and textiles in the form of Woven, knitted or netted fabrics, threads, yarns, fibers, etc., or package form, and which comprise either natural cellulose such as cotton, or artificial silks such as rayon derived from regenerated cellulose fibers produced in either the viscose, cellulose acetate, nitrocellulose or cuprammonium manufacturing processes wherein cellulose derivatives such as cellulose esters (acetate, formate, butyrate, propionate, etc.) and ethers (notably ethyl cellulose, etc), mixed cellulose esters or ethers, etc. are employed. In effecting this treatment, the textile is wetted by immersion in the modified solution or can be passed between rollers coated therewith, after which it is drained, squeezed or centrifuged to remove excess treating solution. After the organic liquid is partially evaporated from the treated material, either spontaneously in air or by exposure to a gentle heat treatment, as by contact with warm air or nitrogen, or by passage over a heated surface, the product is preferably aged for a brief period of time. Thereafter, the impregnated material is immersed in an alkaline precipitating bath of the types above mentioned and preferably one comprising a solution of soda ash or ammonia. It is then finally washed or otherwise processed to recover the desired flame-resistant and laundryproof product.

To a clearer understanding of the invention, the following specific examples are given, which merely further illustrate but are not to be taken as limiting the scope of my invention:

Example I parts by weight of a commercial flame-retardant solution containing 160 gm. TiOz, 292 gm. S13E03, and 32 gm. ZnO and about 11 mols of HCl per liter were diluted with 10 parts of water and 10 parts of isopropyl alcohol. A strip of 6 oz. cotton herringbone twill was saturated by immersion in this solution and the excess squeezed out between mild rolls. The cloth was exposed to moving air for 5 minutes and allowed to stand for 15 minutes longer and then neutralized by immersion in a 15% sodium carbonate solution followed by washing. 30% of the weight of the solution on the cloth was evaporated during the drying period, 7.05 g. TiOz/ 100 gm. fabric along with the usual amount of antimony oxide, etc. was retained by the fibers after the initial wash. This corresponds to a utilization of the reagent. The cloth was then subjected to a series of Sanforize washes and burn tests, described below. After-flame and after-glow were found to be negligible until the char length reached about '7 inches which was considered failure in this set of experiments. The cloth so treated, even after 18 Sanforize washes, exhibited negligible after-flame and after-glow characteristics, The tensile strength of the cloth was found to be not impaired by the above treatment. The tensile strength and tear strength were better than that for control samples treated by the reagent containing no alcohol.

The general procedure used in evaluating the stee /a4 results of the flameproofingtreatment-"inthe foregoing example comprised subjecting the fabric to the indicated number of Sanforize Washes followed by flammability tests on swatches 6 lag time prior to' neutralization and "washing. 5.31 gm. 'IiOz/lOO gm. fabric were found tobe retained, corresponding to a 75%- efliciency. This treatment withstood about 10 Sanforize after each wash. In such type of wash the o washes. (3) Test 2 was repeated except that treated sample is combined with sufficient ballast air was blown over the fabric for 90 minutes unto maintaina'ZS-pound load in the washer at all til 30% of the weight of the solution picked up times. The sample was washed ina conventional had evaporated. 6.3 gm. TiO2/100 gm. fabric type laundry wheel in which it was washed'at I was deposited with 90% efiiciency. The fabric boil for 20 minutes in 15 gallons of water and '75 10 withstood about 17 Sanforize launderings. (4) grams of chip soap and given two ten-minute The third test was repeated but the moisture rinses in 15 gallons of fresh water at 14=0 F. This was evaporated rapidly by passing the cloth over constitutes one wash. This issevere treatment a steam-heated drum. Very go d reagent effland is considered to be the equivalent of about ciency was obtained but the fabric was tendered six household launderings in its eifect on removal 15 to su h ade'gr it practically l These of fiameproofing treatment. v experiments are summarized in the following Flame resistance was measured'on swatches table:

'lest Treatment Drying g ggggg Efficiency Durability Control #1 Full strength retardant... none l5 negligible 58 14 washes.

Control #2 70 ptts. retardant, 30 pts. ...do. 15 very low. 75 1O washes.

Contr'ol#3 sa 90min. s 90 17 washes.

Oontrol#4. same hot drum 30 79.0 excessive tendering.

Example #1 80 pts. retardant, 10 pts. min. moving air... 15 30 00 18 washes water, pts. Isopropanel. Example #2 same .hot drum 33 100 Do,

12 x 2% inches cut parallel to the warp. Each swatch was dried at 105 C. for 30 min.. cooled five min. in a dessicator, and immediately subiected to a burn test comprising clamping the cloth in a vertical position in an enclosed cabinet having mild natural ventilation. A threeeighths-inch diameter luminous gas flame was applied'to the center of the lower edge and enveloping the cloth for a distance of three-quarters of an inch for twelve seconds. After-flame, after-glow, and char length were observed. Char lengths given are the average of three burns. After-flame is the duration of flame after removal of the gas flame.

Example II 6 02. cotton herringbone twill was treatedas in Example I but after squeezing out the excess solution, the cloth was passed over a steamheated metal drum to effect evaporation of alcohol, water and some HCl, totaling 33% of the weight of the solution put on the fabric. After neutralization and washing 7.0 gm. .TlOz/lOO gm. remained in the fabric, corresponding to 100% utilization of the oxides in the'treating solution. In burn tests, as above described, on samples taken from this material after washing the 7-inch char length was reached only after-subjecting them to 18 Sanforize washes. The tensile and tear strengths of the cloth were not impaired. I

To demonstrate the'significance ofthe above examples and-the eifectiveness of the invention, the following control'tests .were made: (1) "6 oz. cotton herringbone twill was. treated similarly with the full strength flame-retarding solution and given a -minute lag at room temperature before neutralizing and washing. 6A gm. TiOz/ 100 gm. fabric were retained corresponding to a utilization of 58% 'of the oxides. This fabric withstood l4 Sanforize washes. Noiimpairment of tensile strength was noted. "(2) The same fabricwas treated with a solutioncomprising '70 parts by weight of the retardantsolution and parts of water allowing a 15 minute Example III Rayon carpet yarn wound in packages was treated with a modified flame-retardant solution of this invention having the composition indicated below. The package comprised a spool of yarn wound on a stainless steel spring core and measured 5 x 5 inches with a 1 E/ -inch center hole. The spring core gave free access of the solution to the inner surface of the yarn. The full strength flame-retardant solution used in Example I was modified as follows: 75 parts by weight of the solution were. diluted with 25 parts by weight of 7% hydrochloric acid solution and then 75 parts by Weight of this mixture was diluted with 25 parts of isopropyl alcohol. The package of rayon yarn was then placed in the cylinder of a conventional package dyeing machine and the solution forced under nitrogen water.

pressure back and forth from center to periphery of the package or cake for ten minutes at room temperature. The cake was centrifuged briefly to remove excess solutions, held in air 10 minutes to allow some evaporation of alcohol and At this point the weight of solution in the package was determined to be about double that of the yarn itself. After more vigorous centrifuging, the liquid content was reduced to about of the weight of the yarn. Air was then blown through the cake in the dyeing machine to obtain final evaporation of the alcohol. 23% NI-Is solution thenforced through the cake followed by cold water rinses alternated with centrifuging to neutralize residual acid and wash out salts, etc. After air drying the yarn taken from the outer and inner surfaces and two equally spaced intermediate points was analysed and the following results were obtained:

This is a very satisfactory flameproofing treatment. The package washed well and was substantially free of precipitated solids outside the fibers.

In a, comparable, similar treatment of the same type package but using the initial flame-retardant solution diluted to 75% by weight with water, an unmanageable slimy precipitate clogged the package at the start of the neutralization step. Ihe treated yarn was therefore unfit for normal subsequent processing.

Example 1V 9. oz. 0. D. Cotton herringbone twill was treated by immersion in the following solution:

Parts by weight Flame-retardant solution 85 Isopropanol 1 7.5 Tertiary butyl alcohol 7.5

The same solution as used in previous examples.

ter equal in weight to the alcohols the results for the cold lag were 58% efiiciency and a 139-pound break strength, and for the hot lag 66% efficiency and 108 pounds. After washing, the samples treated with the alcohol-diluted agent were clean and free of smears or ghosts while tne control samples were mottled and streaked with white or grey patches.

Example V A flame-retardant solution containing 250 gm./l. TiOz, 325 gm./l. SbzOs, 525 gin/l. chlorine as H01, and 325 gin/l. acetic acid was diluted with 50% of its weight of a 50% aqueous isopropanol solution. Rayon blanket material was immersed in this solution, passed between squeeze rolls, heated by passing over adrum to evaporate the alcohol, neutralized and washed. The sample was clean, dust free and flame resistant. Qimilar treatment with the undiluted solution resulted in lower chemical efficiency and a dusty fabric. Corresponding dilution with water, followed by hot lag treatment to give the same degree of treatment, resulted in tendering of the material.

Ezrample VI No. black canvas duck was saturated with a solution obtained as follows: 50 parts by weight of an aqueous flame-retardant solution containing 160 gin/l. T102, 290 gm./l, Sb203, 8i) gm./l. ZnO, and 440 gm./l. chlorine as I-iCl was diluted with 30 parts of isopropanol and parts of tertiary butyl alcohol. The excess was squeezed out and the material exposed to moving air for 15 minutes to evaporate nearly 50% of the weight of the solution picked up. After neutralizing in a 15% solution of soda ash, washing and drying the cloth contained about 12% oxides. The utilization of the reagent was about 95% and no decrease in tensile strength resulted. Similar results were obtained by very short exposure to hot air or by passing the cloth over a heated drum. Dilution of the initial solution with water required nearly two hours drying time at room temperature to obtain the same treatment, while hot drying was impossible due to tendering. Furthermore, when alcohol dilution was not used, the fabric showed marked ghosting due to patches of precipitated oxides which were practically laundryfast. The 12% oxides obtained in this treatment are slightly lower than desired for good permanent fiameproofing. However, this material may be subsequently coated with polyvinyl chloride and this combination treatment gives extremely satisfactory flame resistance.

The dilution of antimony-titanium solutions with an organic liquid in accordance with this invention has substantially no deleterious effect except, in some instances, to decrease stability on storage. However, for all practical uses the solvent-modified solution is amply stable for use in treating cellulosic materials. Accordingly, the amount and kind of solvent employed can be selected to suit the particular use. On the other hand, the modified solution will afford enhanced properties such as better ability to wet and penetrate the fibers of the material being treated While aifording the more important advantages and novel properties which are among the primary objects of the invention.

Although the invention has been described in its adaptation to certain specific embodiments, it obviously is not restricted thereto. Thus, use is generally contemplated of initially acid-stable, water-soluble, volatile, liquid organic solvents, especially monohydroxy alcohols, esters, ketones, and nitriles which contain up to 4 carbon atoms intheir molecule. Examples of useful types of such diluents include methanol, ethanol, propanol, isopropanol, tertiary butanol, secondary butanol, etc., acetone, methyl ethyl ketone, etc., ethyl acetate, ethyl formate, methyl formate, etc., acetonitrile, propionitrile, butyronitrile, etc. It is not necessary that the solvent be completely miscible in the treating solution, but it should be at least 5% soluble therein. Similarly, the amounts of solvent utilized can be varied and can range from, say, about 5'70% of the aqueous solution being modified. Preferably, resort is had to acid-stable forms of diluent but if the reaction with acid is relatively slow, other types can be used. Thus, acetone is said to slowly convert to mesytylene, but this reaction is slow under the conditions prevailing and does not interfere with the operation of this invention provided excessive storage times are avoided. The esters may hydrolyze in the acid solution, but their efiectiveness in the invention remains since water-soluble alcohols result from the hydrolysis. While ethanol and isopropanol comprise preferred types of solvents due to their cheapness and lack of toxicity, tertiary butyl alcohol is also particularly effective and useful. Its efiect is believed due to the fact that, in addition to the physical dilution effect, it slowly reacts with the hydrochloric acid to form tertiary butyl chloride. It has been found that these fiameproofing solutions can be diluted with certain alcohols until the alcohol comprises of the solution by weight and still remain stable enough for normal use. Certain liquids which may be used are limited in amount by virtue of their limited solubility. In this re-' spect it is feasible to use a mixture or a very soluble liquid with a less soluble liquid, e. g., isopropanol and normal butanol to obtain the-"desired dilution.

-As already indicated the invention appliesto aqueous. titanium -antimony solutions; containing free and combined monobasic acids, particularly hydrochloric as j a preferred acid. wI-Iowever, part or all of the acid can be replaced-with an .organic acid such as acetic acid or by an inorganic acid such as hydrobromic or hydriodic acids. One such solutionparticularly well adapted to the process comprises one having substantially .the following composition:

Gmi/l. 'ri'oz '150 Sbz'Oz 291 E61 (total) ""470 Zr-1O 32 It is generally known that such solutions of antimony and titanium in hydrochloriccacid are not always stable although those used in practice are practically stable-for days or "even months. Practicable stability desired in these products dopendson' the required storage time aswell as the existing temperature conditions prior to-a'nd during use. It should be understood that the stability of these solutions is usually increased by increasing the concentration within the ranges specified andby increasing the-acid concentration., .Therefore,iin a'ddingthe organio solvent to .thesefsolutions, due allowance for Y preserving practicable stability should be I made. Thus, when usingsolutions in1the dilute orlow acid rangeiit-mayibe found necessary toadd-more HCl .toprevent 'hydrolysisand precipitation of the :tmetals; .Also, when .usingirelatively large amounts of the solvent, additional H01 may :be required for. the same reason. .Th'ese adjustments in concentration to prevent precipitation are r evices well known'to the art and-whilerthey may be practiced in conjunction with this'invention, they are not considered? apart of; it.

The most desirableresults are obtainedwnen the concentration. of the original aqueous-solution andthe amount and type of organic diluent .used are varied in accordance with the typeof material being treated. This .choice of composition withinthebroad specified range is. particulariyeffective in thecase of rayon, where excellent/results are often obtained by starting witha more dilute aqueous'solution and then adding the organic liquid.

lviodifying agents such 'as sodium silicate, so'dium "tungstate, etc., can be incorporated in the neutralizing bath for purposes'of repressing after-glow. The prooess'of the invention-will also be found to -beeffectivewhen pretreatment of the' cellulosic material withsuchsalts is resorted to.

.The "method of mixing the solventan'd the acid solution is not :limited. -Preferably,.however, and to insure the (maintenance IOf a stab-ie solution, the organic solvent is added .to, the acid solution, withaccompanyingiagitation. I If desired, a the aqueous, acidicsolution can be; mixed with .the organic liquid in the presence of the cllulosic'material .to beftreatedj Thus, ,cotton or rayon staple can be suspended in the aqueous treating solution'and a solvent such as alcohol then added thereto. "Ifhe statue can "then "be separated from the excess solution'by screening, filtering, or draining, and 'thenfini'shed. Alternatively, the material "can be Wetted with fth-e aqueous solution; excessof said s'olution"'can, then beremoved;after 'which the treated material can be immersed in or washed withthe organic liquid, followed-by evaporation and the usual finishing steps.

The composition of the solutionsemployedin the invention expressed-in weight; per cent, include-the following, more .practi'cal ranges with respect to the" major constituents. present: T102 5%-25%, .sbeOs 1'0%30%, with the nionobasic "acid beingi'preferably present in a minimum concentration to insure practical stability. This aqueous rsolution '.can--be diluted, as desired, to "containifroin 5-l0% of dissolved organic liquid in the final mixture. Also, suitable modifying :agents suchasazinc. salts or like compounds can "be incorporated therein and in any desired amounts. .For example, .the addition of from about 25-=35 rg./l. "ofZnO will be. found to be effectively useful in the invention. As previously indioatedthe cellulosicmaterial can be treated byrimmersion in :the modified solution, drained, squeezed, .or centrifuged to remove wexcess solution, and themafter brief aging; partial evaporationiof the I organic liquid, either spontaneously in airior by exposing it to gentle heat-treatment, such as to contact with warm air or nitrogen, etc., is effected. The treated material is then immersed in assolution of a mild alkali an finally-washed.

The detailed chemistry or the reactionbetween cellulose and solutions of -antimonyand titanium in hydrochloric acid is not presentlyfully understood. These solutions render the material flameresistant, even after'numerous 'subsequent launderings, when -.app1ied"andneutralized. -I have found that the quantit :.,of solids as TiOz and SbzOs retained:permanently by the-cellulose'is generally proportional to the concentration of these metals in solution particularly when the atomic'ratio Ti/Sb is'unity. Apparently thereagent solution-swells-the cellulosic fibers permitting the metals to penetratethem while in solution. Upon neutralization, the portion of the flame-retardant solution'outside the fibers is merely precipitated and the resulting precipitated oxides-lost during laundering. For-many of the common-fabrics thi loss of reagentis about 30-to-50 per cent-depending on the type and structure'of the-material. To obtain good flame-resistant properties, from about 17% to 15% by weight of combined oxides is usually required to be retained by the fibers. To obtain treatment in the" range of l5%,-it is necessary to impregnate the fibers with a solution containing about 30% by weight of the combined oxides. 'In accordance with my invention, when such a olution is diluted with an equal volume-of isopropanol and used'in the treatment which includes evaporation of the-alcohol before neutralizing, practically of the oxides are advantageously retainedby the fibers. "A detailed theoretical knowledgedf just how this-improved efficiency isobtaine d isnot presently available butit appears that the alcohoi=diluted solution penetrates the fibers more or less in the same degree as does the more concentrated solution. 'On this basis, at the impregnation step, the combined oxide-content'of the'fibers would'be equivalent to only 7.5%. Howeven-whenthe alcohol is allowed to evaporatej'which it does readily at room temperature the aqueous phase is concentrated to its original 30 andat the same time decreased to a volume that -can"recedeinto-the fibers. As

ization. "This theoryserves' fairly well to explain '11 in a gross physical way the manner in which the volatile solvent achieves the improvement. Other advantageous effects such as better wetting and swelling of the fibers also arise. if the original solution is diluted with water, a similar but less pronounced effect results with respect to the amount of oxides retained by th fiber. However, in such instance a marked undesired tendering of the fabric takes place. Since hydrochloric acid is known to tender cotton and related fibers, the tendering observed on dilution with water is thought due to the acid. The longer time and/or higher temperature required to evaporate the water relative to the time/temperature requirement for evaporation of the alcohol may explain the appearance of the tendering effect. Regardless of theory, the experimental results indicate the superiority of the relatively low boiling organic solvent over the simple water dilution.

When heat is applied to give rapid concentration of the added solution, the evaporating alcohol-water mixture advantageously keeps the fabric temperature below the 80 C. range rather than near 100 C. as is the case with purely aqueous solutions.

My invention presents several advantages over prior methods of cellulose treatments. The most important feature resides in the greatly increased eficiency or utilization of the flameretarding agents. In cases where the utilization is increased from 75% to 100%, the overall saving is often more than the cost of the relatively cheap solvent. In addition, the appearance of the treated material is improved, especially in instances of dark-colored fabric treatment, due to the absence of excess oxides trapped as white powder after the initial washing. Another advantage resides in the fact that thick layers of material or yarn wound on spools or cores can be effectively treated without leaving the unmanageable deposits of oxides occurring when recourse to my organic solvent dilution is not had. Still another advantage is due to the possibility of adjusting the dilution of the solution according to the absorbing power or capacity of the material being treated and the degree of final treatment desired. Thus, for a fabric of a highly porous nature more solvent dilution may be used so that, on evaporation, the correct amount of treating chemical remains with the fibers. For hard dense fabrics, less solvent will be required to gain the desired utilization at the correct treatment level. Thus, by means of this process, both the utilization of the agent and the amount of treatment obtained can be controlled within desired, practical limits. This is of especial value when combination treatments such as that described in Example VI are contemplated. Still another advantage lies in the improved tensile strength of final product obtained in certain instances. For example, the wet strength of paper will be found to be markedly increased by my treatment While good flame-resistance is also im-- parted.

I claim as my invention:

1. A method for treating a cellulosic material to impart flame-resistance characteristics thereto, comprising contacting said material with an acidic aqueous solution of titanium and tervalent antimony diluted with a dissolved, volatile, initially stable organic liquid, said solution having from about 12-600 g./l. of combined titanium and antimony oxides with the weight Ti/Sb ratio in said solution not exceeding 10 and the atomic Sb/Ti ratio not exceeding 2 and said dissolved 12 organic liquid being present in" an amount ranging from 570% by weight of the final solution, removing a portion of said organic liquid from the resulting treated cellulosic product by evaporating such portion therefrom, subjecting said treated product to alkali treatment to neutralize residual acid present after contact of said material with said solution, and then washing the neutralized product in aqueous media and recovering the neutralized, flame-resistant product from said media.

2. A process for fiameproofing a cellulosic material comprising impregnating said material with an acidic aqueous solution of antimonous chloride, titanium chloride, and a volatile organic liquid which is at least 5% soluble in H20 and contains up to 4 carbon atoms in its molecule, said solution ranging in composition from about 3%-20% T102, from 5% to 25% Sb2O3, and between 5% and 70% of dissolved organic solvent, removing a portion of the organic solvent from the impregnated material by contact with air, neutralizing the resulting product by treatment with an alkali, and then washing the neutralized product in an aqueous medium and recovering the resulting flame-resistant material from said media.

3. A method for fiameproofing a cellulosic material comprising impregnating said material with an acidic aqueous solution containing antimonous chloride, titanium chloride, and a dissolved, volatile, initially stable monohydroxy alcohol containing up to 4 carbon atoms in its molecule, said solution ranging in composition from 3%20% T102, from 5% to 25% SbzOs, and between 5% and 70% of dissolved alcohol, evaporating a portion of said alcohol from the impregnated material by contact with warm air, subjecting the resulting product to alkali treatment to effect neutralization thereof, and then washing the resulting neutralized product in an aqueous medium and recovering the fiameresistant material from said media.

4. A process for flameproofing a cellulosic material which comprises impregnating said material with an acidic aqueous solution containing antimonous chloride, titanium chloride, and isopropanol, said solution ranging in composition from 3% to 20% TiOz, from 5%25% SbzOs, and between 5% and 70% of isopropanol, thereafter evaporating a portion of said isopropanol from the impregnated material, subjecting the resulting product to alkali treatment to effect neutralization thereof, and then Washing the neutralized product in aqueous media and recovering the fiame-proofed product.

5. A process for flameproofing a cellulosic material which comprises impregnating said material with an acidic aqueous solution containing antimonous chloride, titanium chloride, and tertiary butanol, said solution ranging in composition from 3% to 20% TiOz, from 5%25% SbzOs, and between 5% and 70% of tertiary butanol, thereafter evaporating a portion of said butanol from the impregnated material, subjecting the resulting product to alkali treatment to effect neutralization thereof, and then washing the neutralized product in aqueous media and recovering the flameproofed product.

6. A process for flameproofing a cellulosic material which comprises contacting said material with an acidic solution of antimonous chloride and titanium chloride containing for each volume 13 of said solution from 0.1 to 3.0 volumes of amono- References Cited in the file of this patent hydroxy alcohol having from l-4 carbon atoms UNITED STATES PATENTS per molecule, thereafter evaporating a portion of the alcohol from the treated cellulosic ma- Nunber Name Date terial, neutralizing the resulting material from 5 37/138 1903 said evaporating treatment with an alkali, and 6 Hopkmson 1944 then washing the neutralized product in an 0566 Lane et 1951 aqueous medium and recovering the flameproofed OTHER REFERENCES matenal- Balthis (Abstract), 692,385, 0. G., vol. 634.

WILLIAM LEONARD DILLS. page 985, May 16, 19% 

1. A METHOD FOR TREATING A CELLULOSIC MATERIAL TO IMPART FLAME-RESISTANCE CHARACTERISTICS THERETO, COMPRISING CONTACTING SAID MATERIAL WITH AN ACIDIC AQUEOUS SOLUTION OF TITANIUM AND TERVALENT ANTIMONY DILUTED WITH A DISSOLVED, VOLATILE, INITIALLY STABLE ORGANIC LIQUID, SAID SOLUTION HAVING FROM ABOUT 12-600G./. OF COMBINED TITANIUM AND ANTIMONY OXIDES WITH THE WEIGHT TI/SB RATIO IN SAID SOLUTION NOT EXCEEDING 10 AND THE ATOMIC SB/TI RATIO NOT EXCEEDING 2 AND SAID DISSOLVED ORGANIC LIQUID BEING PRESENT IN AN AMOUNT RANGING FROM 5-70% BY WEIGHT OF THEFINAL SOLUTION, REMOVING A PORTION OF SAID ORGANIC LIQUID FROM THE RESULTING TREATED CELLULOSIC PRODUCT BY EVAPORATING SUCH PORTION THEREFROM, SUBJECTING SAID TREATED PRODUCT TO ALKALI TREATMENT TO NEUTRALIZE RESIDUAL ACID PRESENT AFTER CONTACT OF SAID MATERIAL WITH SAID SOLUTION, AND THEN WASHING THE NEUTRALIZED PRODUCT IN AQUEOUS MEDIA AND RECOVERING THE NEUTRALIZED, FLAME-RESISTANT PRODUCT FROM SAID MEDIA. 